Highly Improved Mis Photodetector Sensitivity Using Ge Nanocrystals

We report the high performances of Metal-Insulator-Semiconductor Photodetectors (MIS PD) made with crystalline Ge nanocrystals (Ge NCs) as the active absorbers embedded in a silicon dioxide matrix. The Ge NCs have been obtained by a combination of Ge deposition by Molecular Beam Epitaxy (MBE) on tunnel thermal silicon oxide and solid state dewetting processes. Ge NCs structure and morphology are characterized by High Resolution Transmission Electron Microscopy (HRTEM) and Scanning Electron Microscopy (SEM). The photocurrent generation is determined by I-V spectroscopy and Photocurrent spectroscopy. We evidence the role of high quality Ge NCs on photocurrent and explain the high sensitivity of MIS photodetector as a result of transport mechanisms via photoexcited Ge NCs. These results indicate that the crystalline Ge NCs obtained via solid state dewetting can be integrated with opto-electronics and photonics technologies to produce new high performance optoelectronic devices fully compatible with Complementary Oxide Metal (CMOS) technology.